Suspicious your Internet Service Provider is throttling your BitTorrent download of the latest Ubuntu release or some other free and legal bits? File-sharing blog TorrentFreak dug into the data to see the best and worst ISPs when it comes to BitTorrent throttling.

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Data published by the Google-backed Measurement Lab gives a unique insight into the BitTorrent throttling practices of Internet Service Providers (ISPs) all over the world. It reveals, for example, that Comcast was slowing down nearly half of all BitTorrent traffic in the U.S. early 2008, but only 3% last year. In Canada, Rogers has the worst track record as it systematically throttles more than three-quarters of all BitTorrent traffic.

Hundreds of ISPs all over the world limit and restrict BitTorrent traffic on their networks. Unfortunately, most companies are not very open about their network management solutions.

Thanks to data collected by Measurement Lab (M-Lab) the public is now able to take a look at the frequency of these BitTorrent throttling practices. Among other tools, M-Lab runs the Glasnost applicationdeveloped by the Max Planck Institute.

The interactive data set published yesterday spans a two-year period and this initial release covers the period between April 2008 and May 2010. It includes BitTorrent throttling percentages of ISPs in dozens of countries, divided into three-month periods. Below we discuss a few trends and notable findings.

United States

The BitTorrent throttling practices of Comcast, exposed by Robb Topolski and TorrentFreak in 2007, were in part what led to the Measurement Lab research. After an FCC investigation Comcast was ordered to stop slowing down BitTorrent on a large-scale, and the data shows that the company has kept its word.

Early 2008 Comcast limited nearly half (49%) of all BitTorrent traffic but this was reduced to 3 percent by the first quarter of last year. Cox, another heavy throttler, went from 51 percent to 3 percent in the same time period. The data further shows that in 2010, Clearwire was the only U.S. Internet provider that limited more than 10 percent of all BitTorrent traffic, 17 percent to be precise.

Worst: Clearwire (17%)

Best: Comcast and others (3%)

Canada

In Canada, all large ISPs have admitted to slowing down BitTorrent traffic, and some do so to a great extent. Since the start of the measurements Rogers has continuously throttled more than three-quarter of all BitTorrent traffic, and there are no signs that this will stop.

During the first quarter of 2010 the two other large Canadian ISPs, Bell and Shaw, were throttling 16 and 14 percent respectively. Videotron on the other hand has never slowed down more than 7 percent, and only 3 percent during the last measurement year.

Worst: Rogers (78%)

Best: Videotron (3%)

Great Britain

In Great Britain, TalkTalk used to limit a third of all BitTorrent traffic, but this was reduced significantly by the end of 2009. They now only slow down BitTorrent during peak hours which resulted in a 12 percent throttling rate early 2010. Tiscali and BT Group are exposed as the most heavy throttlers while Virgin Media, O2 and BSkyB have had relatively low percentages throughout the measurement period.

Worst: Tiscali and BT Group (27%)

Best: BSkyB (5%)

Other

A quick look at some other countries shows that in Australia none of the large ISPs were throttling BitTorrent traffic heavily in 2010, and the same can be said for Sweden and France. In The Netherlands UPC used to throttle heavily, but this was no longer the case early 2010.

In Germany, Kabel Deutschland seems to be the poorest choice for BitTorrent users (36%), and in Poland UPC has to be avoided as they limit 87 percent of all BitTorrent traffic.

Those who are interested in seeing how their own ISP performs can take a look at the full dataset at deeppacket.info. The researchers promise to release more recent data in the future, and it will be interesting to see how the various throttling habits of ISPs develop.

For those who have a choice, which us unfortunately not always the case, the data can definitely help to make an informed decision when signing up at a new Internet Provider. Photo by Feliciano Guimarães.